The first measurements of large anisotropic modulation of long-wavelength light with a large on/off ratio and low driving voltage propagating along the plane of InGaAs/InAlAs multiple quantum well (MQW) structures grown by molecular beam epitaxy (MBE) are reported. Photocurrent response and optical modulation of waveguide pin diodes is measured for incident light polarization parallel and perpendicular to the MQW layers emitting from a color center laser. The incident-light power and wavelength dependence of on/off ratio are also determined. 相似文献
The levels of formaldehyde (FA) and acetaldehyde (AA) in polyethylene terephthalate (PET) bottles and in commercial mineral water are reported. All the water samples bottled in Japan contained detectable levels of FA (10.1-27.9 μg l-1) and AA (44.3-107.8 μg l-1). Of 11 European bottled water samples, eight did not contain either FA or AA, while the remaining three had detectable levels of FA (7.4-13.7 μg l-1) and AA (35.9-46.9 μg l-1). In three North American bottled water samples, two contained FA (13.6 and 19.5 μg l-1) and AA (41.4 and 44.8 μg l-1), and one did not. Regardless of the region of origin, all the sterilized water samples contained FA and AA, whilst in contrast, none of the unsterilized water without carbonate contained FA or AA. Of the carbonated water samples, three contained FA and AA, and one did not. When fortified with FA and AA, the commercial water sample without otherwise detectable FA and AA was able to reduce levels, although the commercial water sample containing FA and AA could not. The presence of bacteria in the commercial water samples was investigated using an ATP-based bioluminescent assay and heterotrophic plate count method. The commercial water without FA and AA contained heterotrophic bacteria, whilst the commercial water with FA and AA did not contain detectable bacteria. It is suggested that in this case both FA and AA migrated from PET materials, but were subsequently decomposed by the heterotrophic bacteria in the unsterilized water. 相似文献
An instrumented flow cell in the form of a cylinder with differentially heated end walls and adiabatic sidewalls was flown
on STS-95 as the Japan-US Thermal Science Accelerometer Project (JUSTSAP). The purpose of the experiment was to map disturbances
in the thermal field during the course of a Shuttle mission in order to correlated them with various mission events and to
determine if any global transport could be detected from second order, non-zero time average flows resulting from periodic
accelerations (g-jitter).
Significant disturbances in the thermal field were noted each time the Shuttle changed attitude, such as the maneuver to -Z
solar inertial, which is done periodically for thermal conditioning. Burns from the main thrusters associated with the launch
and retrieval of the Spartan satellite produced overturning flows, as might be expected. During extended periods in which
the attitude was held constant, the perturbations to the thermal field correlate extremely well with calculated accelerations
from gravity gradient and drag. Fair agreement was found between the observed temperature perturbations and those predicted
from a modification of the analytical model developed by Bejan and Tien (B&T) for the flow and heat transfer in an infinite
cylinder with a constant axial thermal gradient. A full three-dimensional computational fluid dynamic analysis with more realistic
thermal boundary conditions provided better agreement after adjustments were made to account for the heat flow away from the
measuring thermistors.
Once calibrated with a reliable thermal model, the flow cell was found to serve as a high-precision accelerometer, capable
of measuring the quasi-steady acceleration with a sensitivity of better than 0.1 micro-g in the presence of the higher amplitude
g-jitter typical of Shuttle operations. Further, it was found that the gravity gradient acceleration accounted for virtually
all of the observed quasi-steady accelerations during such extended periods. The thermal response time of the JUSTSAP was
too slow to expect to see the effects of fluctuating first order flows resulting from the vibrational environment of the Shuttle.
However, an indication of a change in the thermal field near the ends of the flow cell was seen during periods of crew exercise
that may possibly be attributed to circulating eddies resulting from the higher order terms in the momentum equation. At higher
amplitudes, these second order effects can produce non-zero time average flows of a global nature, as can the start-up transients
in first-order periodic flows. No such effects were observed, thus it is possible to place an upper limit on the integrated
power spectral density of the vibrational environment experienced as well as the nature of the start-up transients of the
periodic flows. 相似文献
For a fuel jet flame stabilized by a two-dimensional, backward-facing step exposed to a subsonic air stream, an experimental study was made of the dependence of the ignition front of the flame on various physical quantities, such as the width of the fuel nozzle, the height of the step, the boundary-layer thickness of the air stream at the step, and the velocity of fuel ejection of the outer air stream. Propane was ejected parallel to the air stream from the nozzle placed at the top of the step. It is shown that when the boundary layer of the air stream is laminar, the distance from the nozzle to the ignition front, xt, is given by the equation, where bn is the width of the fuel nozzle, Uf the fuel ejection velocity at the nozzle, Ua the outer stream velocity of the air, δ* the displacement thickness of the boundary layer of the air stream at the step, and α a dimensionless experimental constant. The location of the flame front does not depend on the height of the step. Further, the length of the recirculation zone formed downstream of the step and the burning limits of the flame were measured. 相似文献
The mechanical yielding behavior of the shape memory polyurethane (SMP) and its composite samples were investigated to verify
the effect of addition of hindered phenol. The composite samples were prepared using SMP as matrix and hindered phenol (AO-80)
as filler, and then tensile tests were carried out at a range of temperatures and with different fixed crosshead speeds. According
to the tensile data at 25 °C, the yield stress was increased by adding AO-80. In terms of the Eyring theory, the activation
volume of deformation units decreased with increase of the amount of AO-80 added. This is because the packing of the hard
segments is enhanced by addition of AO-80. Consequently, it was suggested that the yield process is caused by the rotation
of hard segment domains within the deformed plastic domains composed of glassy soft segments. 相似文献
Hybrid Recycle System (HRS) is proposed as an advanced recycle system. The HRS consists of improved fluoride volatility reprocessing and vibration packing MOX fuel fabrication processing. For the former, a part of U is volatilized as hexafluoride with diluted F2 gas, and then residual U and Pu are volatilized with concentrated F2 gas. Plutonium content of the mixed fluoride gas can be adjusted as desired by controlling the U fluorination reaction in the first step. The U is highly decontaminated and the mixture gas of UF6 and PuF6 is not purified. The fluoride mixture is reacted with H2O and H2 and directly converted to the mixed oxide grain for the vibration packing. The HRS can reduce the costs of reprocessing and fuel fabrication, the amounts of radioactive wastes and the probability of Pu proliferation. 相似文献
A report is given of the 1st confirmed outbreak of Albizia versicolor poisoning in Malawi and the 1st natural outbreak reported in sheep and goats. Approximately 800 animals are estimated to have died over a 9-year period on a government farm near Lake Malawi. Deaths occurred exclusively from August to December when ripe dry pods that fell to the ground were ingested. The major clinical signs were hyperaesthesia, wild running, lateral recumbency with rapid leg movements, nystagmus and rapid blinking. Approximately 75% of clinical cases made a full and rapid recovery. Sheep more often showed signs of poisoning than goats which was attributed to inherent susceptibility rather than selective feeding. The majority of animals affected were under 1 year of age. A series of experiments was conducted and all animals dosed with 6.4 g/kg or more of dry pods died with typical clinical signs. Although A. versicolor is well known to the local population there appeared to be no appreciation of its toxicity. Poisonings are probably rare under traditional management systems. 相似文献
The development of advanced technology for the spent nuclear fuel reprocessing should be achieved not only considering cost, non proliferation and reduction of radioactive wastes but also corresponding to both spent nuclear fuels of LWR and FBR.
We have proposed an ion exchange process for reprocessing using a new type ion exchanger developed to chemical method of U enrichment technology. This process possess possibility of a sharp cut in cost, since this ion exchanger is characterized by rapid adsorption-desorption rate dominating the treatment rate.
From the basic experimental results, this reprocessing process has been constructed by 3 ion exchanger columns which consist of a main separation column, the uranium-refining column and the plutonium-refining column.
Comparing ion exchange process with the conventional Purex process, this ion exchange process has many advantages such as the decrease in the number and size separation equipment, solvent-spent free and alkaline-liquid-spent free. With these advantages, this process is estimated that the construction cost of reprocessing process is greatly reduced comparing to the conventional process. 相似文献